One-year clinical outcomes of ST segment elevation myocardial infarction patients treated with emergent percutaneous coronary intervention: the impact of thrombus burden.

OBJECTIVE: To investigate the impact of thrombus burden on 1-year clinical outcomes in patients who underwent emergent percutaneous coronary intervention (PCI) for ST segment elevation myocardial infarction (STEMI).

MATERIAL AND METHOD: Angiographic evidence of intracoronary thrombus adversely affects the outcome of PCI in STEMI. Large thrombus burden (> or = 2 times vessel diameter) has been shown to be a significant predictor of major adverse cardiac events (MACE). The impact of thrombus burden in Asian patients who undergo PCI in STEMI has not been described. This is an observational cohort of patients with STEMI from June 1, 2008 through May 31, 2011, who underwent emergent PCI (primary or rescue). The patients were categorized into two groups according to the angiographic thrombus burden, large thrombus burden (> or = 2X vessel diameter size, LTB) and small thrombus burden (< 2X vessel diameter size, STB). MACE was defined as the composite of death, repeat myocardial infarction, target vessel revascularization and stent thrombosis.

RESULTS: 202 patients were enrolled, 72% were male and the mean age was 60 years old. 134 patients (66%) presented with an occluded infarct related artery. Primary PCI was performed in 90.6% of the patients and the remainder underwent rescue PCI. One hundred eleven (55%) patients were categorized into the STB group and 91 patients (45%) into the LTB group. The use of aspiration thrombectomy was significant higher in the LTB group (LTB 80.2% vs. STB 60.44%, p = 0.002). A higher proportion of patients in the STB group underwent direct stenting strategy (STB 32.4% vs. LTB 18.7%, p = 0.027). There were no significant differences in final TIMI grade 3 flows and procedural success between the groups. Overall, in hospital, mortality was 13.4% and there were no significant differences among the groups. At 1-year follow-up, there was no significant difference in cumulative MACE-free survival in the LTB vs. STB group (82.4% vs. 79.3%, 95% confidence interval for the difference: -8.0% to 13.8%, p = 0.59).

CONCLUSION: In the current study, large thrombus burden is not an independent predictor of 1-year cumulative MACE in STEMI patients who were treated with emergent PCI.